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Heat Transfer Characteristics outside the Condenser of a Rotating Heat Pipe Grinding Wheel with a Lateral Air impinging jet

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Journal of Thermal Science 2021年第2期30卷 493-503页

作者： CHEN Jiajia ZHANG Liyong FU Yucan QIAN Ning JIANG Huafei YANG Lin College of Mechanical and Electronic Engineering Nanjing Forestry UniversityNanjing 210037China College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Jiangsu Wind Power Generation Engineering&Technology Center Nanjing 210023China

This study numerically analyzed the heat transfer characteristics outside the condenser of a rotating heat pipe grinding wheel(RHP-GW).The goal of this investigation is to determine the optimal structure and parameters for the condenser section of *** fin height(f=0-7 mm),rotational Reynolds number(Rer=1602-6408)and jet Reynolds number(Rej=42379-108302)were analyzed under input heat flux of 4000 W/m2.A fully developed flow was imposed at the outlet of the *** showed that the optimal heat transfer rate was obtained for fin height of 5 mm,which improved the average Nusselt number by 84%compared to the structure without fins.A critical Rej for each Rer that the impinging jet can reach the condenser section was *** critical Rej value increases with Rer,which is in the range from 42379 to 61215 and 61215 to 80050 for Rer=6408 and Rer=9610,respectively.

关键词： rotating heat pipe grinding wheel impinging jet heat transfer numerical analysis

Large Eddy Simulation of Coherent Structure of impinging jet

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Journal of Thermal Science 2005年第2期14卷 150-155页

作者： MingzhouYU LihuaCHEN HanhuiJIN JianrenFAN CollegeofMechanicalandEnergyEngineering ZhejiangUniversityHangzhouChina310027

The flow field of a rectangular exit, semi-confined and submerged turbulent jet impinging orthogonally on a flat plate with Reynolds number 8500 was studied by large eddy simulation (LES). A dynamic sub-grid stress model has been used for the small scales of turbulence. The evolvements such as the forming, developing, moving,pairing and merging of the coherent structures of vortex in the whole regions were obtained. The results revealed that the primary vortex structures were generated periodically, which was the key factor to make the secondary vortices generate in the wall jet region. In addition, the eddy intensity of the primary vortices and the secondary vortices induced by the primary vortices along with the time were also analyzed.

关键词： large eddy simulation impinging jet coherent structure.

Quadrature Method of Moments for Nanoparticle Coagulation and Diffusion in the Planar impinging jet Flow

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Chinese Journal of Chemical Engineering 2007年第6期15卷 828-836页

作者：于明州林建忠熊红兵 The State Key Laboratory of Fluid Power Transmission and Control Zhejiang UniversityHangzhou 310027China China Jiliang University Hangzhou 310018China

A computational model combining large .eddy simulation with quadrature moment method was em-ployed to study nanoparticle evolution in a confined impinging jet. The investigated particle size is limited in the transient regime, and the particle collision kernel was obtained by using the theory of flux matching. The simulation was validated by comparing it with the experimental results. The numerical results show coherent structure acts to dominate particle number intensity, size and polydispersity distributions, and it also induce particle-laden iet to be diluted by .the *** evolution of particle dynarnics *** impinging jet flow are strongly related to the Rey-nolds number and nozzle-to-plate distance, and their relationships were analyzed.

关键词： nanoparticle coagulation impinging jet large eddy simulation quadrature moment method

Analysis of disagreement between numerically predicted and experimental heat transfer data of impinging jet

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Journal of Central South University of Technology 2006年第5期13卷 486-490页

作者：周萍叶良春周孑民杨莺 School of Energy Science and Engineering Central South University

The method of numerical simulation was applied to investigate the effects of jet impinging plate thickness and its thermal conductivity on the local heat flux distribution along the impinging plate. The results show that the two factors have great effects on the heat flux distribution. The non-uniformity of the local heat-flux on the impinging plate surface gets more profound as the plate becomes thicker and thermal conductivity gets larger. When Reynolds number is 5000, the ratio of nozzle-to-plate spacing to nozzle diameter is 5 and thermal conductivity is 16W/(m·K), and even for the plate with only 25μm in thickness, the non-uniformity of the heat flux cannot be neglected. When the plate thickness is 50 μm, only when thermal conductivity is as small as 1W/(m·K), the heat flux curve can be approximately treated as an iso-heat-flux boundary. In the experimental research, a real non-iso-heat-flux boundary is treated as an iso-heat-flux boundary, which would result in under-estimated Nusselt number value in the stagnation zone and an over-estimated value outside. Such an experimental Nusselt number distribution is taken to evaluate turbulent model, and the conclusion would be drawn that the turbulent model over-predicts the stagnation heat transfer. This is one of the important reasons why many literatures reported that k-ε turbulent model dramatically over-predicts the impinging jet heat transfer in the stagnation region.

关键词： impinging jet experiment numerical simulation heat flux

APPLICATION OF TWO VERSIONS OF A RNG BASED k-ε MODEL TO NUMERICAL SIMULATIONS OF TURBULENT impinging jet FLOW

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Journal of Hydrodynamics 2003年第2期15卷 71-76页

作者： Chenqingquang XuZhong ZhangYong-jian DepartmentofFluidEngineering Xi‘anJiaotongUniversityXi’an710049China SchoolofMechanicalandElectronicEngineering ShandongUniversityofScienceandTechnologyTai‘an271019China

Two independent versions of the RNG based k ε turbulence model in conjunction with the law of the wall have been applied to the numerical simulation of an axisymmetric turbulent impinging jet flow field. The two model predictions are compared with those of the standard k ε model and with the experimental data measured by LDV (Laser Doppler Velocimetry). It shows that the original version of the RNG k ε model with the choice of C ε1 =1.063 can not yield good results, among them the predicted turbulent kinetic energy profiles in the vicinity of the stagnation region are even worse than those predicted by the standard k ε model. However, the new version of RNG k ε model behaves well. This is mainly due to the corrections to the constants C ε1 and C ε2 along with a modification of the production term to account for non equilibrium strain rates in the flow.

关键词： RNG based k ε turbulence model impinging jet non equilibrium strain rate

Application of Optical Flow Analysis to Shadowgraph Images of impinging jet

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Journal of Flow Control, Measurement & Visualization 2020年第4期8卷 173-187页

作者： Masato Hijikuro Masayuki Anyoji Interdisciplinary Graduate School of Engineering Sciences Kyushu University Fukuoka Japan

In this study, we apply the optical flow method to the time-series shadowgraph images of impinging jets using a high-speed video camera with high spatial and temporal resolution. This image analysis provides quantitative velocity vector fields in the object space without tracer particles. The analysis results clearly capture the details of the coherent vortex structure and its advection from the shear layer of the free jet. Although the results still leave challenges for the quantitative validation, the results show that this analysis method is effective for understanding the details of the physical phenomenon based on the quantitative values extracted from the shadowgraph images.

关键词： impinging jet Optical Flow Shadowgraph Image Analysis Velocity Vector

EFFECT OF WALL FUNC TION IN NUMERICAL STUDY ON TURBULENT impinging jet

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Transactions of Nanjing University of Aeronautics and Astronautics 2001年第1期18卷 29-34页

作者：徐惊雷徐忠黄淑娟张堃元南京航空航天大学能源与动力学院西安交通大学流体工程系

A low Reynolds number k-ε model is used in the numeri cal study on a circular semi-confined turbulent impinging jet . The result is c ompared with that of the standard k-ε model and a refined k-ε mode l, which re-consi-dered the fluctuating pressure diffusion term in the dissipa tion rate equation (ε-equation) through modeling. It shows that the low Re ynolds number k-ε model and the standard k-ε model yield very poor performance, while the predicting ability of the refined k-ε model is mu ch improved , especially for the turbulent kinetic energy k. So it can be co ncluded that the poor performance of the standard k-ε model is owing to t he incorrect considering the effect of the fluctuating pressure diffusion term r ather than the use of the wall function near the wall just as presumed in the re ference.

关键词： impinging jet turbulence fluctuating pressure diffusion term wall function

THREE-DIMENSIONAL MEAN AND TURBULENCE CHARACTERISTICS OF AN impinging DENSITY jet IN A CONFINED CROSSFLOW IN NEAR FIELD

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Journal of Hydrodynamics 2004年第6期16卷 737-742页

作者： FANJing-yu WANGDao-zeng ZHANGYan ShanghaiInstituteofAppliedMechematicsandMechanics ShanghaiUniversityShanghai200072China

The three-dimensional mean and turbulence characteristics of an impingingdensity jet in a confined cross-flow were numerically investigated using the RNG turbulence *** comparison of the subregion structures and gross features between the numerical results and theexperimental data show good agreement. The velocity, Turbulent Kinetic Energy (TKE) andconcentration distributions of the impinging jet in near field were obtained and analyzed. Theresults indicate that the flow and concentration fields of the impinging jet in the crossflowexhibit distinguished three-dimensionality in the near field. There exist upstream wail vortices anddownstream wall jet zones in the impinging region, and the TKE and concentration decays areasymmetrical in relation to the stagnation point. The lateral concentration distribution range inthe impinging region spreads considerably. The enhanced entrainment and mixing of the impinging jetin the confined crossflow are mostly associated with the impinging action and lateral expansion inthe impinging region. The presence of the bottom wall restrains the formation of the span-wiserollers in the transverse jet region and vertical entrainment and mixing in the impinging region andthe transition re-gioa

关键词： impinging jet crossflow entrainment mixing

Experimental and numerical investigations on the vortical structures of an impinging jet in crossflow

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Journal of Shanghai University(English Edition) 2006年第3期10卷 279-280页

作者：张燕 Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 P.R. China

The objective of this dissertation is to investigate the impinging jet under the influence of crossflow. It has been known that there exist jet shear layer, impingement on the bottom wall, interactions between the induced wall jet and the ambient crossflow in near field. There are few intensive studies of the impinging jet in crossflow at home and abroad due to the complexities of flow, such as the formation and evolution of the vortical structures, interactions among vortices, while researches on the temporal and spatial evolution of these vortical structures can promote the practical applications in environment engineering, hydroelectricity engineering, etc., and provide the basis for flow control and improvement through revealing the inherent mechanism and development of the vortical structures.

关键词： vortical structure impinging jet crossflow PIV measurement LES.